1-aminoanthraquinone-2-sulphonic acid



Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE WORKS, Inc, on

NEW YORK, N. Y., A CORPORATION OF DELAWARE1-AMINOANTI-IRAQUINONE-Z-SULYHONIG ACID No Drawing. Application filedApril 10, 1928, Serial- No. 269,035, and in Germany April 23, 1927.

The present invention relates to the production of 1 aminoanthraquinone2 sulphonic acid.

I have found that ,l-aminoanthraquinone- 5 2-sulphonic acid can easilybe prepared by sulphonatingl-aminoanthraquinonebymeans of fumingsulfuric acid in the presence of an alkali metal or alkali earth metalsulfate.

As sulphonating agent I prefer fuming sulfuric acid containing about10-20% S0 whereby the temperature at which reaction takes place variesbetween about 100120 C. depending on the strength of the fuming sulfuricacid used.

When working in this manner substantially pure1-amino-anthraquinone-2-sulphonic acid is obtained. By adding alkali-,or earth alkali-, metal sulfates, one avoids the simultaneous oxidationand formation of by-prod- 2 ucts such asl-amino-anthraquinone-2A-disulphonic acid, which otherwise always takeplace.

The following example illustrates my invention without limiting itthereto, the parts being by Weight:

Ewample: 18 parts of 1-amino-anthraquinone and 18 parts of anhydroussodium sulfate are introduced in 1850 parts of sulfuric acid monohydrateand 550 parts of fuming sulfuric acid, containing 65% S0 are added tothis solution at 7 0 C. in the course of one hour. The temperature isthen raised to 120 0., the melt is maintained at this temperature untila sample is soluble in hot water, then cooled to 30 C. and stirred into6000 parts of water. The l-amino-anthraquinone-2-sulphonic acidthereupon crystallizes out in the form of its sodium salt.

I claim:

1. Process,whichcomprisesinsulphonating l-aminoanthraquinone with fumingsulfuric acid in the presence of a compound of the group consisting ofalkali metal sulfates and alkali earth metal sulfates.

2. Process, which comprises sulphonating 1- aminoanthraquinone by meansof fuming sulfuric acid containing about 10-20% $0 at a temperaturebetween about 100 C. and about 120 C. in the presence of an alkali metalsulfate.

3. Process, which comprises sulphonating l-aminoanthraquinone by meansof fuming sulfuric acid containing about 1020% SO at a temperaturebetween about 100 C. and about 120 C. in the presence of a compound ofthe group consisting of sodium sulfate and potassium sulfate.

4. Process which comprises introducing 4.8 parts by weight ofl-amino-anthraquinone and 48 parts by weight of anhydrous sodium sulfatein 1850 parts by weight of sulfuric acid monohydrate, adding 550 partsby weight of fuming sulfuric acid containing S0 at a temperature of 6070within one hour, heating the mixture to 120 C. until a sample is solublein hot water and precipitating the sodium salt of thel-aminoanthraquinone-2-sulphonic acid by means of 6000 parts by weightof water.

In testimony whereof I have hereunto set my hand.

KLAUS WEINAND.

